Some electronic devices such as inductors and transformers employ magnetic cores that generate an induced magnetic flux. Many conventional magnetic cores are assembled together as two separate magnetic core members that form a magnetic flux circuit. One approach employs a pair of generally E-shaped magnetic core members that are assembled such that the open ends of each arm join with each other to provide the induced magnetic flux path. Each arm has a connecting surface designed to align with like size and shape surface areas on the opposing magnetic core member. Another approach employs the assembly of a generally E-shaped magnetic core member assembled to a planar-shaped plate core member.
In the above-described conventional core assemblies, the two magnetic core members both have the same general overall width and length. As a consequence, the two magnetic core members must be properly aligned to minimize magnetic flux losses. The alignment procedure is difficult to implement in some applications, such as in the assembly of core members for use as a transformer or inductor that is integrated into a printed circuit board. The installation of an upper core member onto a lower core member through the circuit board may occur in a blind operation, thus inhibiting assurance of precise alignment of the two core members.
Misalignment of the two magnetic core members reduces the effective cross-sectional area of the conventional core device. The magnetic flux passing from one core member to the other misaligned core member is forced to crowd to the remaining contact surface to complete the magnetic flux path, which is known as flux crowding. Increased flux density or crowding may lead to core saturation near the adjoining surfaces which may produce unwanted thermal energy (heat). Additionally, not all of the densified magnetic flux will make it through the reduced size of the adjoining surfaces, thereby causing some magnetic flux to pass outside of the core, which is known as flux fringing. With flux fringing, magnetic flux passes into the surrounding environment and possibly into the nearby circuitry where eddy currents are generated, energy is wasted, and noise may be introduced.
Flux fringing and flux crowding may occur in conventional magnetic core assemblies where the two magnetic core members are shifted relative to each other and/or are rotated in a skewed alignment. In either situation, a reduction in the cross-sectional area of the magnetic flux circuit is realized which reduces overall inductance. Additionally, a reduction in the cross-sectional area increases the flux density or crowding in the device and also results in flux fringing. The resultant reduction in cross-sectional area of the magnetic flux circuit due to shifted and/or skewed alignment of the two core members therefore results in reduced performance.
Accordingly, it is therefore desirable to provide for a magnetic core device made up of the assembly of two magnetic core members that does not suffer from a reduced magnetic flux path area due to the alignment procedure. It is further desirable to provide for a magnetic core device having two core members that may be, easily aligned to minimize flux fringing and flux crowding so as to optimize performance of the magnetic core device. It is particularly desirable to provide for such a magnetic core device that may be assembled onto a circuit board, such as a printed circuit board, where shifting and/or skewed alignment of the core members may occur.